kevent: Don't poll for nonzero timeouts < 1us.

Instead of truncating nanosecond timeouts to zero here and polling, we
should round up to a delay of at least a tick, just like all the other
timespec syscalls.

Fixed in NetBSD kern_event.c v1.62 and FreeBSD r247804.

ok millert@ visa@

diff --git a/sys/kern/kern_event.c b/sys/kern/kern_event.c
index 81b5918..1af10f0 100644 (file)
--- a/sys/kern/kern_event.c
+++ b/sys/kern/kern_event.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: kern_event.c,v 1.98 2018/08/20 16:00:22 mpi Exp $     */
+/*     $OpenBSD: kern_event.c,v 1.99 2018/09/04 02:38:25 cheloha Exp $ */
 
 /*-
  * Copyright (c) 1999,2000,2001 Jonathan Lemon <jlemon@FreeBSD.org>
@@ -694,8 +694,7 @@ kqueue_scan(struct kqueue *kq, int maxevents, struct kevent *ulistp,
        const struct timespec *tsp, struct proc *p, int *retval)
 {
        struct kevent *kevp;
-       struct timespec ats;
-       struct timeval atv, rtv, ttv;
+       struct timespec ats, rts, tts;
        struct knote *kn, marker;
        int s, count, timeout, nkev = 0, error = 0;
        struct kevent kev[KQ_NEVENTS];
@@ -706,39 +705,36 @@ kqueue_scan(struct kqueue *kq, int maxevents, struct kevent *ulistp,
 
        if (tsp != NULL) {
                ats = *tsp;
-               if (timespecfix(&ats)) {
-                       error = EINVAL;
-                       goto done;
-               }
-               TIMESPEC_TO_TIMEVAL(&atv, &ats);
-               if (atv.tv_sec == 0 && atv.tv_usec == 0) {
+               if (!timespecisset(&ats)) {
                        /* No timeout, just poll */
                        timeout = -1;
                        goto start;
                }
-               itimerround(&atv);
+               if (timespecfix(&ats)) {
+                       error = EINVAL;
+                       goto done;
+               }
 
-               timeout = atv.tv_sec > 24 * 60 * 60 ?
-                   24 * 60 * 60 * hz : tvtohz(&atv);
+               timeout = ats.tv_sec > 24 * 60 * 60 ?
+                   24 * 60 * 60 * hz : tstohz(&ats);
 
-               getmicrouptime(&rtv);
-               timeradd(&atv, &rtv, &atv);
+               getnanouptime(&rts);
+               timespecadd(&ats, &rts, &ats);
        } else {
-               atv.tv_sec = 0;
-               atv.tv_usec = 0;
+               timespecclear(&ats);
                timeout = 0;
        }
        goto start;
 
 retry:
-       if (atv.tv_sec || atv.tv_usec) {
-               getmicrouptime(&rtv);
-               if (timercmp(&rtv, &atv, >=))
+       if (timespecisset(&ats)) {
+               getnanouptime(&rts);
+               if (timespeccmp(&rts, &ats, >=))
                        goto done;
-               ttv = atv;
-               timersub(&ttv, &rtv, &ttv);
-               timeout = ttv.tv_sec > 24 * 60 * 60 ?
-                   24 * 60 * 60 * hz : tvtohz(&ttv);
+               tts = ats;
+               timespecsub(&tts, &rts, &tts);
+               timeout = tts.tv_sec > 24 * 60 * 60 ?
+                   24 * 60 * 60 * hz : tstohz(&tts);
        }
 
 start: